Viscoelastic materials are substances that exhibit both viscous and elastic properties when deformed. This means they can stretch or compress like a rubber band (elastic behavior) while also flowing or changing shape over time under stress (viscous behavior). Common examples include polymer materials, biological tissues, and certain types of foams. These materials respond to applied forces in a time-dependent manner, meaning their behavior can change based on how long a force is applied. This unique combination of properties makes viscoelastic materials useful in various applications, such as shock absorbers, medical devices, and packaging materials.